package com.lagou.sqlSession;

import com.lagou.config.BoundSql;
import com.lagou.pojo.Configuration;
import com.lagou.pojo.MappedStatement;
import com.lagou.utils.GenericTokenParser;
import com.lagou.utils.ParameterMapping;
import com.lagou.utils.ParameterMappingTokenHandler;

import java.beans.IntrospectionException;
import java.beans.PropertyDescriptor;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.sql.*;
import java.util.ArrayList;
import java.util.List;

public class SimpleExecutor implements Executor{

    @Override
    public <E> List<E> query(Configuration configuration, MappedStatement mappedStatement, Object... params) throws SQLException, ClassNotFoundException, NoSuchFieldException, IllegalAccessException, InstantiationException, IntrospectionException, InvocationTargetException {
        Connection connection = configuration.getDataSource().getConnection();

        String sql = mappedStatement.getSql();
        BoundSql boundSql =getBoundSql(sql);

        PreparedStatement preparedStatement = connection.prepareStatement(boundSql.getSqlText());
        String paramterType = mappedStatement.getParamterType();
        Class<?> paramtertypeClass =getClassType(paramterType);

        List<ParameterMapping> parameterMappingList = boundSql.getParameterMappingList();
        for(int i=0;i<parameterMappingList.size();i++){
            ParameterMapping parameterMapping = parameterMappingList.get(i);
            String content = parameterMapping.getContent();
            //反射
            Field declaredField = paramtertypeClass.getDeclaredField(content);
            //暴力访问
            declaredField.setAccessible(true);
            Object o = declaredField.get(params[0]);
            preparedStatement.setObject(i+1,o);
        }

        //5.执行sql
        ResultSet resultSet = preparedStatement.executeQuery();

        //6.封装返回结果集
        String resultType = mappedStatement.getResultType();
        Class<?> resultTypeClass = getClassType(resultType);

        ArrayList<Object> objects = new ArrayList<>();
        while (resultSet.next()){
            Object o = resultTypeClass.newInstance();
            //元数据
            ResultSetMetaData metaData = resultSet.getMetaData();
            for (int i=1;i<=metaData.getColumnCount();i++){
                //字段名
                String columnName = metaData.getColumnName(i);
                //字段的值
                Object value = resultSet.getObject(columnName);
                //
                PropertyDescriptor propertyDescriptor = new PropertyDescriptor(columnName, resultTypeClass);
                Method writeMethod = propertyDescriptor.getWriteMethod();
                writeMethod.invoke(o,value);

            }
            objects.add(o);
        }

        return (List<E>) objects;
    }

    @Override
    public Object executeCUD(Configuration configuration, MappedStatement mappedStatement, Object... params) throws Exception {
        Connection connection = configuration.getDataSource().getConnection();

        String sql = mappedStatement.getSql();
        BoundSql boundSql =getBoundSql(sql);

        PreparedStatement preparedStatement = connection.prepareStatement(boundSql.getSqlText());
        String paramterType = mappedStatement.getParamterType();
        Class<?> paramtertypeClass =getClassType(paramterType);

        List<ParameterMapping> parameterMappingList = boundSql.getParameterMappingList();
        for(int i=0;i<parameterMappingList.size();i++){
            ParameterMapping parameterMapping = parameterMappingList.get(i);
            String content = parameterMapping.getContent();
            //反射
            Field declaredField = paramtertypeClass.getDeclaredField(content);
            //暴力访问
            declaredField.setAccessible(true);
            Object o = declaredField.get(params[0]);
            preparedStatement.setObject(i+1,o);
        }

        //5.执行sql
        preparedStatement.execute();
        return null;
    }

    private Class<?> getClassType(String paramterType) throws ClassNotFoundException {
        if(paramterType !=null){
            Class<?> aClass = Class.forName(paramterType);
            return aClass;
        }
        return null;
    }

    private BoundSql getBoundSql(String sql) {
        ParameterMappingTokenHandler parameterMappingTokenHandler = new ParameterMappingTokenHandler();
        GenericTokenParser genericTokenParser = new GenericTokenParser("#{", "}", parameterMappingTokenHandler);
        String parseSql = genericTokenParser.parse(sql);
        List<ParameterMapping> parameterMappings = parameterMappingTokenHandler.getParameterMappings();
        BoundSql boundSql = new BoundSql(parseSql, parameterMappings);
        return boundSql;
    }
}
